Hello,
this is my first post, so first of all I want to thanks all the coppelia team for your work. It's great!

I found that relative path have to be relative to the vrep install dir. Usually we have scenes that have to be aligned with some project versioning system, so it's unlikely that they are archived in the vrep install dir folder. I would like to have the possibility of launching scenes from their relative path.

I took some time to propose you a patch for the vrep.sh file. It checks if there is a scenes relative to the user working directory, make it absolute (by appending the relative path to the given scene). This is the diff:

Nothing else is changed but the fact that if the scene file exists with a path relative to the user working directory, the user working directory is added. Every other parameter is left as it was.
If the file does not exist as relative, $SCENE will be empty. Otherwise, it will contain the absolute path plus a space, to separate it from the other parameters (${1+"$@"}) when recalling them in the last command.
I hope it can be useful to someone.